The present invention relates to a workpiece seat, and more particularly to an angle-adjustable one.
In conventional working technique, one usually suffers from a positioning difficulty if working a workpiece at a specific angle is desired, e.g. milling a plane at 37.degree. or drilling on a plane at 42.degree. with respect to the reference plane. It has been proposed that gauge blocks are placed beneath a workpiece to incline it to the desired angle and then to fix it by a vise in order to work thereon. Using gauge blocks, however, demands a complicated calculation. Furthermore, gauge blocks are expensive and should be a measuring tool but not inserts beneath the workpiece to be easily damaged. Thus, it is developed a fixture which can fix thereon a workpiece which can then be worked at a specific angle. Nevertheless, the gauge of the workpiece is inevitably similar.
In order to overcome the above shortcomings encountered by the prior art, an angle-adjustable workpiece seat, as shown in FIGS. 1 & 2, has been marketed. The seat includes a base 10 having a top sliding rail 11 having a T-shaped crosssection and a scale 12, a sliding member 13 having a sliding T-shaped groove 14, a scale 15 and a V-shaped positioning surface 16, a barrel 17 having a head 18 sliding in sliding groove 14, and a bolt 19 screwing from the bottom of base 10 into barrel 17 in order to firmly urge sliding member 13 against base 10. The relative position or angle between sliding member 13 and base 10 can be adjusted by sliding sliding groove 14 on sliding rail 11. After a long period of use, it has been revealed that such seat still has the following disadvantages:
1. The locking force between sliding member 13 and base 10 by pulling member 13 toward base 10 by bolt 19 is relatively small so that the locking between member 13 and base 10 will get loose if a larger working load is applied on the workpiece and thus a working error is introduced into the workpiece.
2. Since bolt 19 threads into barrel 17 from the bottom of base 10, such seat must be turned by 90.degree. or 180.degree. in order to tightly screw bolt 19 on barrel 17 after the angle adjustment between member 13 and base 10 has been made, this being not only inconvenient but also prone to incur a relatively displacement therebetween which requires a renewed angle adjustment therebetween.
3. Working or machining barrel 17 and rail and groove 11 & 14 of T-shaped crosssection is relatively complicated and expensive.
4. V-shaped surface 16 can only fit thereon a workpiece of a specific gauge and thus multiple sliding members 13 must be provided if working workpieces of different gauges on base 10 is desired.
5. The angle between member 13 and base 10 can only be determined by the eyes of the user viewing scales 12, 15 and cannot be examined whether it is accurate or not if a workpiece is to be precisely worked.